The present invention relates generally to Intelligent Network (IN) telecommunication services and, more specifically, to a method of and a system for delivering calls to subscribers in plural service provider domains.
Modern Intelligent Network (IN) telecommunication systems provide several telecommunication and network services. The services available to a subscriber, either for free or on a subscription basis, are contained in so-called user profile information, stored in Service Control Point (SCP) equipment of the telecommunications system.
Due to the deregulation of public telecommunication, present IN telecommunication systems are comprised of plural service provider domains which may operate in different or the same geographical areas. The number, type and charging of services may vary among the service providers.
Number Portability (NP) allows subscribers to change service provider domains without changing their subscriber or telephone number. A call to a ported subscriber will be delivered to the actual location of the ported subscriber despite dialling of the original subscriber number.
In an article by W. Lautenschlager et al., xe2x80x9cRouting Service for the Provision of Number Portabilityxe2x80x9d, International Switching Symposium (ISS ""97), vol. 2, 21-26 September 1997, pages 234-242, Toronto several network methods for the implementation of number portability have been discussed.
Besides the so-called full IN routing, wherein for each call in a network a routing data base or routing service is queried for obtaining necessary routing information, a call to a ported subscriber generally will invoke interrogation of the service provider domain at which the called subscriber was originally registered, also called the donor domain. From the routing information obtained, the call will be delivered to the ported subscriber in the actual service provider domain identified by the routing information.
Routing information associated with a ported subscriber may be provided in separate local or global NP data base equipment or in the SCP of the home service provider or donor domain, such as also disclosed by U.S. Pat. No. 5,598,464. The routing information provided may comprise the (or a reference to the) actual location of the ported subscriber in a particular service provider domain, or a reference to a so-called gateway providing an interface between service provider domains. Gateways are used, for example, if service providers for competitive or other reasons do not wish to directly disclose sensitive domain information to their competitors.
One of the problems associated with NP is the requirement of delivering calls to ported subscribers in accordance with telecommunication and network services available to a ported subscriber in his service provider domain.
British patent application 2,280,334 discloses a method of invoking a telephone user profile in connection with a user initiated routing of a call. User service profile information is stored in all the switches of a telephone network, using an intermediate central computer.
Besides excessive storage space requirements and a strict scheme for updating all the switches in the case of changes in the service profile information of a subscriber, in particular if different service provider domains are involved, service providers may have a genuine requirement based, among others, on providing competitive services, not to disclose information as to service subscriptions etc. Accordingly, in practice, service providers will prefer to store service profile information of their subscribers in the SCP equipment of their own service domain.
In such a case, after a call has been routed to the actual service provider domain of a ported subscriber, a further inquiry of the SCP equipment of this domain has to be initiated to find out whether or not the ported subscriber has availed himself of services, at least services pertinent to the delivery of a call. Those skilled in the art will appreciate that such a further inquiry increases the delay in the delivery of calls to ported subscribers, compared to non-ported subscribers. However, it is an objective of the telecommunication practice to keep call set-up times as small as possible.
It is an object of the present invention to provide an efficient method of and a system for delivering calls to ported, subscribers in accordance with services available to a ported subscriber.
According to the invention, in a first aspect thereof, there is provided a method of delivering calls to called subscribers in a service provider domain of an Intelligent Network (IN) telecommunication system comprising plural service provider domains, each such domain comprising interconnected Service Switching Point (SSP) and Service Control Point (SCP) equipment, the SSP being operable for delivering a call from a calling subscriber to a called subscriber, and the SCP being operable for controlling telecommunication and network services available to a subscriber in his service provider domain, wherein for ported subscribers routing information is provided and calls to the ported subscribers are delivered in accordance with such routing information, the method comprises the steps of:
providing porting information, at least for ported subscribers, the porting information being associated with routing information and information as to services available to ported subscribers, in particular services relating to the delivery of calls, and
delivering calls to called ported subscribers in accordance with the routing information and the service information provided, wherein
calls to ported subscribers not having services relating to the delivery of calls are delivered without inquiring the SCP, equipment of the service provider domain of the ported subscribers, and wherein
calls to ported subscribers having services relating to the delivery of calls are delivered by inquiring the SCP equipment of the service provider domain of the ported subscribers in accordance with the service information provided.
In the method according to the invention, for each subscriber porting information is available concerning the actual location of the called subscriber and whether or not interrogation of the SCP of the actual service provider domain is required. The SCP may contain or have access to the porting information.
If the called subscriber is within his home service provider or donor domain, the call will be delivered after SCP consultation for porting information following established principals of IN by the SSP equipment under the control of the SCP and the telecommunication and network services available to the called subscriber.
However, if the porting information obtained indicates that the called subscriber is ported to a different service provider domain, routing information is retrieved, identifying the ported subscriber at the other service provider domain.
Following the method of the invention, the routing information is directly linked to information at least indicating whether the call has to be delivered in accordance with services available to the called subscriber. Thus, information as to the telecommunication and network services of the called subscriber becomes directly available with completion of the routing and the call to the ported subscriber can be delivered in accordance with its respective service profile. This without any separate interrogation step whether or not the called subscriber has availed himself of services pertinent to the delivery of calls. As a minimum, only information has to be disclosed relating to whether a ported subscriber comprises services and not the complete service profile at the other service provider domain.
Those skilled in the art will appreciate that the method according to the invention minimizes signaling overhead. With the method according to the invention, each service provider maintains his own service information. Thus, service providers are principally not forced to update common network data bases or the like which, for setting up a reliable update procedure, essentially requires disclosure of competitive service information. However, common network data bases are still applicable, if desired.
The method according to the invention hardly requires additional resources for storage and update of porting information. The service information part of the porting information, in its simplest form, may comprise a so-called service flag or trigger. Such a service flag or trigger essentially comprises a single data bit or a few data bits, indicating whether and under what conditions services, in particular services relating to call delivery, are available to the called ported subscriber. A service flag trigger may also involve the conditional setting of a so-called mask bit or mask bits, simply called xe2x80x9cmaskxe2x80x9d.
In a further embodiment of the method according to the invention, the porting information may be retrieved from a dedicated data base operable for storing routing information of ported subscribers.
In a preferred embodiment of the method according to the invention, the porting information inclusive routing and service information, is retrieved from the SCP of the home service provider domain of the ported subscriber.
In a yet further embodiment of the method according to the invention, the routing information includes information as to whether the subscriber is ported to a different part of his own service provider domain, that is such a part operable for controlling telecommunication and network services.
With this feature, it is possible to provide (additional) telecommunication and network services to subscribers not directly available in the part of the service provider domain to which the subscriber connects. That is, a subscriber can be locally ported within his own home service provider domain for providing (the additional) services. With the method of the invention, calls to a locally ported subscriber will be supported by the services available, without any delays other than for obtaining the porting information.
Those skilled in the art will appreciate that the (additional) service profile information may be comprised in the same SCP of a service provider domain, however at different locations thereof and accessible through a local number portability lookup.
Following the invention, porting information may be retrieved at each call to each subscriber or, selectively, only for calls to actually ported subscribers.
The invention further provides a system for delivering calls to called subscribers in a service provider domain of an Intelligent Network (IN) telecommunication system comprising plural service provider domains, each such domain comprising interconnected Service Switching Point (SSP) and Service Control Point (SCP) equipment, the SSP being operable for delivering a call from a calling subscriber to a called subscriber through intermediate exchanges or switches, and the SCP being operable for controlling telecommunication and network services available to a subscriber in his service provider domain, the system comprises:
means for storing routing information of a ported subscriber,
means for storing porting information, at least for ported subscribers, the porting information being associated with routing information and information as to services available to ported subscribers, in particular services relating to the delivery of calls,
means for retrieving and evaluating porting information, operatively connected such that
calls to ported subscribers not having services relating to the delivery of calls are delivered without inquiring the SCP equipment of the service provider domain of the ported subscribers, and in that
calls to ported subscribers having services relating to the delivery of calls are delivered by inquiring the SCP equipment of the service provider domain of the ported subscribers in accordance with the service information provided.